The invention relates to a biological fertilizer that comprises yeasts for fixing atmospheric nitrogen, and decomposing insoluble compounds containing phosphorus, potassium and/or carbon. The invention also relates to methods for manufacturing the biological fertilizer, and methods for using the biological fertilizer to increase crop yields.
Use of fertilizer is essential in supporting the growth of high yield crops. Of the basic nutrients that plants need for healthy growth, large amounts of nitrogen (taken up as NO3xe2x88x92 or NH4+), phosphorus (taken up as H2PO4xe2x88x92), and potassium (taken up as K+) nutrients are required by most crops on most soils (Wichmann, W., et al., IFA World Fertilizer Use Manual). Such large amounts of nitrogen, phosphorus, and potassium nutrients are supplied mainly in the form of mineral fertilizers, either processed natural minerals or manufactured chemicals (K. F. Isherwood, 1998, Mineral Fertilizer Use and the Environment, United Nations Environmental Programme Technical Report No. 26.). The development and use of mineral fertilizers since the 1940s has permitted significant increases in crop yields on the same to slightly less amount of cropland to support today""s enormous population. Without such advances in agriculture, a great amount of pastures and forests would have been converted into cropland. (K. F. Isherwood, 1998, Mineral Fertilizer Use and the Environment, United Nations Environmental Programme Technical Report No. 26.)
Despite the importance of mineral fertilizers in providing mankind with abundant agricultural products, the harm done to the environment has been recognized in the recent years. Mineral fertilizers may incurred damages to soils. For example, most nitrogen fertilizers may acidify soils, thereby adversely affecting the growth of plants and other soil organisms. Extensive use of chemical nitrogen fertilizers may also inhibit the activity of natural nitrogen fixing microorganisms, thereby decreasing the natural fertility of soils. Mineral fertilizers may also introduce toxic substances into soil and produce. For example, phosphate fertilizers processed from rock phosphate often contain small amounts of toxic elements, such as cadmium, which may build up in soil and be taken up by plants. The long term use of mineral fertilizers may also cause severe environmental pollution. For example, the loss of nitrogen and phosphate fertilizers due to leaching and soil erosion has led to contamination of soil and ground water, and eutrophication of surface water. Cleaning up polluted soil and water has been a complicated and difficult task. The cost for such a task is also astronomical.
In search for a solution to the problem, some are going back to organic fertilizers. As is well known, organic fertilizers come from many different sources. Types of organic fertilizer include farm wastes, such as crop residues and animal manures; residues from plant and animal products, such as wood materials; and town wastes, such as sewage (Wichmann, W., et al., IFA World Fertilizer Use Manual). Organic fertilizers are usually low in nutrients and less effective in supporting plant growth. For example, the total nutrients in cattle manure is less than 2%, and the nitrogen nutrients therein are more difficult to be effectively utilized due to their losses into the environment (K. F. Isherwood, 1998. Mineral Fertilizer Use and the Environment, United Nations Environmental Programme Technical Report No. 26.). Normally, very large amount of organic fertilizers have to be applied to soil. To reach high crop yield, organic fertilizers have only been used to supplement mineral fertilizers. Therefore, the problems with mineral fertilizers cannot be satisfactorily solved by substituting mineral fertilizer with organic fertilizer. Furthermore, organic fertilizers also have created environmental problems. For example, some organic fertilizers, if unprocessed, contains pathogenic microorganisms, such as E. coli, Salmonella, and Coccidae. Organic fertilizers may also contain toxic chemicals and may produce undesirable odor. The use of organic fertilizer also contribute to the contamination and eutrophication of the natural water system. Therefore, in many parts of the world, including the United States, laws and regulations have been established imposing considerable restriction on both the composition and the usage of organic fertilizers.
Biological fertilizers utilizing microorganisms have been proposed as alternatives to mineral fertilizers. Naturally occurring nitrogen fixing microorganisms including bacteria, such as Rhizobium, Azotobacter, and Azospirillum, (See for example, U.S. Pat. No. 5,071,462) and fungi, such as Aspergillus flavus-oryzae, (See, for example, U.S. Pat. No. 4,670,037) have been utilized in biological fertilizers. Naturally occurring microorganisms capable of solubilizing rock phosphate ore or other insoluble phosphates into soluble phosphates have also been utilized in biological fertilizers either separately (e.g., U.S. Pat. No. 5,912,398) or in combination with nitrogen fixing microorganisms (e.g., U.S. Pat. No. 5,484,464). Genetically modified bacterial strains have also been developed and utilized in biological fertilizers. An approach based on recombinant DNA techniques has been developed to create more effective nitrogen fixing, phosphorus decomposing, and potassium decomposing bacterial strains for use in a biological fertilizer, see, for example, U.S. Pat. No. 5,578,486; PCT publication WO 95/09814; Chinese patent publication: CN 1081662A; CN 1082016A; CN 1082017A; CN 1103060A; and CN 1109595A.
However, the biological fertilizers that are based on naturally occurring microorganisms are generally not efficient enough to effectively replace mineral fertilizers. It is therefore important to develop biological fertilizers that can replace mineral fertilizers in supplying nitrogen, phosphorus, and potassium to crops for producing high quality agricultural products while avoiding the problems associated with mineral fertilizers. The present invention provides a biological fertilizer based on yeasts, which can replace mineral fertilizers.
Citation of documents herein is not intended as an admission that any of the documents cited herein is pertinent prior art, or an admission that the cited documents are considered material to the patentability of the claims of the present application. All statements as to the date or representations as to the contents of these documents are based on the information available to the applicant and does not constitute any admission as to the correctness of the dates or contents of these documents.
The present invention relates to biological fertilizers. The biological fertilizer compositions of the invention may comprise up to six different yeast cell components, an organic substrate component and/or an inorganic substrate component. In particular, the yeast cell components of the composition are capable of fixing atmospheric nitrogen, decomposing insoluble minerals or compounds, decomposing complex carbon materials or compounds, overproducing growth factors, or overproducing ATP, respectively.
The present invention uses yeasts that are commercially available and/or accessible to the public, such as but not limited to Saccharomyces cerevisiae. The yeast cell components of the invention are produced by culturing yeast cells under activation conditions such that the abilities of the cells to fix atmospheric nitrogen, to decompose insoluble phosphorus minerals or compounds, to decompose insoluble potassium minerals or compounds, and to decompose complex carbon materials or compounds are activated or enhanced. The yeast cells can also be cultured under conditions such that their abilities to produce excess growth factors or ATP are activated or enhanced. Yeast cells exhibiting such activities are useful in converting nitrogen from the atmosphere to nitrogenous compounds that can be used by plants as nutrients, releasing the otherwise insoluble phosphorus, potassium and carbon from minerals and complex molecules, such that these elements become available in a form that the plant can utilize for growth. Some yeast cells in the fertilizer are used for supporting other plant nutrient-providing yeast cells by supplying them with growth factors and ATP.
The present invention also involves the use of a wide variety of organic and inorganic materials in the fertilizer to support the growth of the yeast strains of the present invention. In one embodiment, the fertilizer is produced by mixing coal-mine waste and rock phosphate with the yeast strains. In another embodiment, the fertilizer is produced by mixing animal manures, and optionally, a biological disinfectant, with the yeast strains. In yet another embodiment, the fertilizer is produced by mixing sludge from sewage water treatment plant and a biological disinfectant with the yeast strains.
The invention also relates to methods for manufacturing the fertilizer comprising mixing, drying, and packing the yeast strains of the present invention and the organic and/or inorganic materials.
The invention further relates to methods for using the fertilizer of the present invention. The biological fertilizers of the present invention are used to support and enhance the growth and maturation of a wide variety of plants.